Monitor the total memory of a process and its children

monitor_memory.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from subprocess import run, PIPE
import os
from time import sleep
import click


@click.command()
@click.argument('pid', type=click.INT)
@click.option('--every', type=click.INT, default=5)
def monitor(pid, every=5):
    print(f"Monitoring PID {pid}...")

    username = os.environ['USER']
    ret = run(f"ps -o pid,ppid,pgid,comm,rss -u {username} "
              f"| grep {pid}", shell=True, stdout=PIPE)

    max_mem = 0

    try:
        while True:
            mem = sum((int(line.split()[-1]) for line in
                       ret.stdout.decode('utf-8').splitlines())) / 1024 / 1024
            if mem > max_mem:
                max_mem = mem

            print(f"Current usage = {mem:.2f} GB")
            print(f"Max usage = {max_mem:.2f} GB")

            sleep(every)
            print("\033[F\033[K\033[F\033[K", end='')
    except KeyboardInterrupt:
        print(f"\nCurrent usage = {mem:.2f} GB")
        print(f"Max usage = {max_mem:.2f} GB")


if __name__ == "__main__":
    monitor()